How to speed application up (if possible)

Question

I have an ARD 2560, which I communicate with through a special written Delphi 7 program (USB handling is done in the D-7 program).

I use the command syntax:

<REG> <COMMAND) <:> <NUMBER> <CR>

where
REG is A - K (the registers in the ARD 2650)
COMMAND can be a 2-chars command, but mostly 1-char commands.

EG: AR:255<cr> // AR configures DDRA to out- or in-put , depending on the parameter - (here 255 / 0xff) .
AI:0<cr> Read port A input (actually return content of ARD2560 port A input register)
AO:<number><CR> Send Number to port A (and return result to D-7 ).
......

All those command are valid for Reg A to Reg K.

The response time from transmit (d7) to I ("D/7") get the answer is approx. 1 1/2 second. I have a feeling that my code is a big, big kludge (it actually works), but I would like any advice(s) to to improve code // speeding it up.

If I drop the line:

 if (char (pport[0] == '*' )) // '*' can be 'A' to 'K' 

The response time increases to appr. 2 seconds.

(sorry that there are no comments!)

Here's the code:

#include <Esplora.h>
void setup()
{
 Serial.begin(9600);
}
void loop()
{
 String chr;
 if (Serial.available() > 0)
 {
 String pport = Serial.readStringUntil(':');
 {
 String pos = Serial.readStringUntil('\n');
 if (char (pport[0] == 'A' )) /* A */
 {
 if (pport == "AR")
 {
 DDRA = pos.toInt();
 DOCRLF("//AR+", pos.toInt());
 }
 else
 if (pport == "AI")
 {
 if (DDRA == B00000000)
 {
 Serial.print(PORTA);
 chr = "//AI";
 }
 else
 {
 chr ="//AI-";
 }
 DOCRLF(chr , pos.toInt());
 }
 else
 if (pport == "AO")
 {
 if (DDRA == B11111111)
 {
 PORTA = pos.toInt();
 chr = "//AO+";
 }
 else
 {
 chr = "//AO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "AU")
 {
 Serial.print(PORTA);
 DOCRLF("//AU+", pos.toInt());
 }
 else
 if (pport == "ABW")
 {
 PORTA = pos.toInt();
 DOCRLF("//ABW+", pos.toInt());
 }
 else
 if (pport == "ABR")
 {
 Serial.print(PORTA);
 DOCRLF("//ABR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'B' )) /* B */
 {
 if (pport == "BR")
 {
 DDRB = pos.toInt();
 DOCRLF("//BR+", pos.toInt());
 }
 else
 if (pport == "BI")
 {
 if (DDRB == B00000000)
 {
 Serial.print(PORTB);
 chr = "//BI+";
 }
 else
 {
 chr = "//BI-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "BO")
 {
 if (DDRB == B11111111)
 {
 PORTB = pos.toInt();
 chr = "//BO+";
 }
 else
 {
 chr = "//BO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "BU")
 {
 Serial.print(PORTB);
 DOCRLF("//BU+", pos.toInt());
 }
 else
 if (pport == "BBW")
 {
 PORTB = pos.toInt();
 DOCRLF("//EBW+", pos.toInt());
 }
 else
 if (pport == "BBR")
 {
 Serial.print(PORTB);
 DOCRLF("//BBR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'C' )) /* C */
 {
 if (pport == "CR")
 {
 DDRC = pos.toInt();
 DOCRLF("//CR+", pos.toInt());
 }
 else
 if (pport == "CI")
 {
 if (DDRC == B00000000)
 {
 Serial.print(PORTC);
 chr = "//CI+";
 }
 else
 {
 chr = "//CI-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "CO")
 {
 if (DDRC == B11111111)
 {
 PORTC = pos.toInt();
 chr = "//CO+";
 }
 else
 {
 chr = "//CO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "CU")
 {
 Serial.print(PORTC);
 DOCRLF("//CU+", pos.toInt());
 }
 else
 if (pport == "CBW")
 {
 PORTC = pos.toInt();
 DOCRLF("//CBW+", pos.toInt());
 }
 else
 if (pport == "CBR")
 {
 Serial.print(PORTC);
 DOCRLF("//CBR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'D' )) /* D */
 {
 if (pport == "DR")
 {
 DDRD = pos.toInt();
 DOCRLF("//DR+", pos.toInt());
 }
 else
 if (pport == "DI")
 {
 if (DDRD == B00000000)
 {
 Serial.print(PORTD);
 chr = "//DI+";
 }
 else
 {
 chr = "//DI-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "DO")
 {
 if (DDRD == B11111111)
 {
 PORTD = pos.toInt();
 chr = "//DO+";
 }
 else
 {
 chr = "//DO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "DU")
 {
 Serial.print(PORTD);
 DOCRLF("//DU+", pos.toInt());
 }
 else
 if (pport == "DBW")
 {
 PORTD = pos.toInt();
 DOCRLF("//DBW+", pos.toInt());
 }
 else
 if (pport == "DBR")
 {
 Serial.print(PORTE);
 Serial.println("//DBR+");
 }
 }
 else
 if (char (pport[0] == 'E' )) /* E */
 {
 if (pport == "ER")
 {
 DDRE = pos.toInt();
 DOCRLF("//ER+", pos.toInt());
 }
 else
 if (pport == "EI")
 {
 if (DDRE == B00000000)
 {
 Serial.print(PORTE);
 chr = "//ER+";
 }
 else
 {
 chr = "//ER-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "EO")
 {
 if (DDRE == B11111111)
 {
 PORTE = pos.toInt();
 chr = "//EO+";
 }
 else
 {
 chr = "//EO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "EU")
 {
 Serial.print(PORTE);
 DOCRLF("//EU+", pos.toInt());
 }
 else
 if (pport == "EBW")
 {
 PORTE = pos.toInt();
 DOCRLF("//EBW+", pos.toInt());
 }
 else
 if (pport == "EBR")
 {
 Serial.print(PORTE);
 DOCRLF("//EBR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'F' )) /* F */
 {
 if (pport == "FR")
 {
 DDRF = pos.toInt();
 DOCRLF("//FR+", pos.toInt());
 }
 else
 if (pport == "FI")
 {
 if (DDRF == B00000000)
 {
 Serial.print(PORTF);
 chr = "//FI+";
 }
 else
 {
 chr = "//F1-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "FO")
 {
 if (DDRF == B11111111)
 {
 PORTF = pos.toInt();
 chr = "//FO+";
 }
 else
 {
 chr = "//FO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "FU")
 {
 Serial.print(PORTF);
 DOCRLF("//FU+", pos.toInt());
 }
 else
 if (pport == "FBW")
 {
 PORTF = pos.toInt();
 DOCRLF("//FBW+", pos.toInt());
 }
 else
 if (pport == "FBR")
 {
 Serial.print(PORTF);
 DOCRLF("//FBR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'G' )) /* G */
 {
 if (pport == "GR")
 {
 DDRG = pos.toInt();
 DOCRLF("//GR+", pos.toInt());
 }
 else
 if (pport == "GI")
 {
 if (DDRG == B00000000)
 {
 Serial.print(PORTG);
 chr = "//GI+";
 }
 else
 {
 chr = "//GI-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "GO")
 {
 if (DDRG == B11111111)
 {
 PORTG = pos.toInt();
 chr = "//GO+";
 }
 else
 {
 chr = "//GO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "GU")
 {
 Serial.print(PORTG);
 DOCRLF("//GU+", pos.toInt());
 }
 else
 if (pport == "GBW")
 {
 PORTG = pos.toInt();
 DOCRLF("//GBW+", pos.toInt());
 }
 else
 if (pport == "GBR")
 {
 Serial.print(PORTG);
 DOCRLF("//GBR+", pos.toInt());
 }
 }
 else
 if (char (pport[0] == 'H' )) /* H */
 {
 if (pport == "HR")
 {
 DDRH = pos.toInt();
 DOCRLF("//HR+", pos.toInt());
 }
 else
 if (pport == "HI")
 {
 if (DDRH == B00000000)
 {
 Serial.print(PORTH);
 chr = "//HI+";
 }
 else
 {
 chr = "//HI-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "HO")
 {
 if (DDRH == B11111111)
 {
 PORTH = pos.toInt();
 chr = "//HO+";
 }
 else
 {
 chr = "//HO-";
 }
 DOCRLF(chr, pos.toInt());
 }
 else
 if (pport == "HU")
 {
 Serial.print(PORTH);
 DOCRLF("//HU+", pos.toInt());
 }
 else
 if (pport == "HBW")
 {
 PORTH = pos.toInt();
 DOCRLF("//HBW+", pos.toInt());
 }
 else
 if (pport == "HBR")
 {
 Serial.print(PORTH);
 DOCRLF("//HBR+", pos.toInt());
 }
 }
 else
 if (pport == "RA")
 {
 int aport = (pos.toInt());
 if (aport > -1 && aport < 16)
 {
 Serial.println (" OK ");
 }
 }
 else
 if (pport == "KO")
 {
 Serial.print("//KO+");
 if (DDRA == B11111111)
 {
 Serial.print("A");
 }
 else
 {
 Serial.print("a");
 }
 if (DDRB == B11111111)
 {
 Serial.print("B");
 }
 else
 {
 Serial.print("b");
 }
 if (DDRC == B11111111)
 {
 Serial.print("C");
 }
 else
 {
 Serial.print("c");
 }
 if (DDRD == B11111111)
 {
 Serial.print("D");
 }
 else
 {
 Serial.print("d");
 }
 if (DDRE == B11111111)
 {
 Serial.print("E");
 }
 else
 {
 Serial.print("e");
 }
 if (DDRF == B11111111)
 {
 Serial.print("F");
 }
 else
 {
 Serial.print("f");
 }
 if (DDRG == B11111111)
 {
 Serial.print("G");
 }
 else
 {
 Serial.print("g");
 }
 if (DDRH == B11111111)
 {
 Serial.print("H");
 }
 else
 {
 Serial.print("h");
 }
 Serial.println();
 }
 }
 }
}
void DOCRLF (String txt, int vval)
{
 Serial.print(txt);
 Serial.println(vval);
}

• Edgar Bonet: You wrote: "readStringUntil('\n')". Your problem looks to me like a timeout in readStringUntil(). Are you sure your Delphi program does send that LF character? And your serial port driver does not convert it to CR?
• Michel Keijzers: First check which commands take so much time, 1.5 seconds is a lot for a CPU. When knowing what statements take so much time, you can pinpoint how to improve the performance, high likely it's only one statement (or several times the same statement).
• Juraj: why 9600 baud rate? CR is \r not \n. \n is LF

Answer 1

This is not really a proper answer to your question. As I mentioned in a comment, I believe your actual problem is the Delphi program not sending the LF character you sketch expects. Instead, I am giving here a coding style suggestion: do not repeat yourself.

Whenever you find yourself coding with copy-paste, you should try to simplify the program using arrays and/or loops. Below is a suggested alternative version of your loop(), with most of its redundant repetitive repetitions removed:

struct port_t {
 volatile uint8_t *ddr;
 volatile uint8_t *port;
};
static const port_t ports[] = {
 { &DDRA, &PORTA },
 { &DDRB, &PORTB },
 { &DDRC, &PORTC },
 { &DDRD, &PORTD },
 { &DDRE, &PORTE },
 { &DDRF, &PORTF },
 { &DDRG, &PORTG },
 { &DDRH, &PORTH },
 { NULL, NULL }, // there is no port I
 { &DDRJ, &PORTJ },
 { &DDRK, &PORTK },
 { &DDRL, &PORTL }
};
void loop()
{
 // Read the command line.
 if (Serial.available() == 0) return;
 String pport = Serial.readStringUntil(':');
 String pos = Serial.readStringUntil('\n');
 // The "KO" command reads all ports.
 if (pport == "KO") {
 Serial.print("//KO+");
 for (char port_id = 'A'; port_id <= 'H'; port_id++) {
 if (*ports[port_id - 'A'].ddr == 0xff)
 Serial.print(port_id);
 else
 Serial.print(tolower(port_id));
 }
 Serial.println();
 return;
 }
 // Identify the port to act on.
 char port_id = pport[0];
 if (port_id < 'A' || port_id > 'L' || port_id == 'I') {
 Serial.println(F("Error: unknown port."));
 return;
 }
 port_t port = ports[port_id - 'A'];
 // Perform the requested action.
 String command = pport.substring(1);
 String chr = String("//") + port_id + command;
 if (command == "R") {
 *port.ddr = pos.toInt();
 DOCRLF(chr + "+", pos.toInt());
 } else if (command == "I") {
 if (*port.ddr == 0)
 Serial.print(*port.port);
 else
 chr += "-";
 DOCRLF(chr , pos.toInt());
 } else if (command == "O") {
 if (*port.ddr == 0xff) {
 *port.port = pos.toInt();
 chr += "+";
 } else {
 chr += "-";
 }
 DOCRLF(chr, pos.toInt());
 } else if (command == "U" || command == "BR") {
 Serial.print(*port.port);
 DOCRLF(chr + "+", pos.toInt());
 } else if (command == "BW") {
 *port.port = pos.toInt();
 DOCRLF(chr + "+", pos.toInt());
 }
}

• Kristian Sander: I wanna thank you. As a newbie to C (C++) in Arduino programming I wanted to do it in a way you just showed me. Using "ARRAYS" but I did not know how to. (A little easier in Delphi- I think ). ANyway I want to give you a very special "Thanks a lot" for 2 reasons. 1: You showed me at way to solve the problem and 2: by supplying a code example.
• Kristian Sander: @ Juraj: DARN - I need to update my basics. Thanks a lot for correcting (always thougt that '\n' == CR.) Now I'm wiser (a least a little !)
• Kristian Sander: I changed the '/n' to '\r' added LF to to the D-7 tx-routine (now transmits <str> + CRLF . That totally improved the speed on the old "KLUDGE"- version. Responsetime is no > 1.sec (I can' measure to be precise.) Added my "missing" rutines (void Setup() + DOCRLF(..) ) to the new version, compiled , corrected a typo , compiled again- and VOILA - it worked. Much faster than before - response time again far under 1 sec (unmeasured) . I am very ,very pleased. Thank you to both of you.
• Juraj: @KristianSander, you can set faster baud rate. try 115200 baud or more
• Kristian Sander: @Juraj: I will set the Baud-rate later, when the D-7 program is improved. There is a speed increase (opimizing code) there, too .